Analysis and improvement of a statistical model-based voice activity detector

From investigation of a statistical model-based voice activity detector (VAD), it is found that the likelihood ratio defined in the VAD has a fundamental problem at the offset regions of speech signals. Thus, we analyze the behavioral mechanism of the likelihood ratio, identify the reason for the unwanted phenomenon, and propose a solution based on a smoothed likelihood ratio. Objective test results show that the proposed method gives significant improvement to the original VAD. Additionally, the improved VAD results in performance even superior to G.729B and comparable to AMR VAD option 2.